Datasheet

LOGIC INPUT COMPATIBILITY GAIN AND OFFSET ADJUSTMENTS
+Full-Scale
AllBits
Logic0
1LSB
Rangeof
OffsetAdjust
OffsetAdjust
Translates
theLine
DigitalInput
AllBits
Logic1
AnalogOutput
Full-Scale
Range
GainAdjust
RotatestheLine
- Full-Scale
MSBonAll
OthersOff
Bipolar
Offset
Rangeof
GainAdjust
» ±0.3%
» ±0.3%
R
R=1k:A ,A , ,WRCLR
0 1
3k:D ...D
0 15
ESDProtectionCircuit
6.8V 5pF
Digital
Input
-V
CC
+V
CC
INPUT CODING
INTERNAL REFERENCE
OUTPUT VOLTAGE SWING
Offset Adjustment
DAC712
www.ti.com ................................................................................................................................................. SBAS023A – SEPTEMBER 2000 – REVISED JULY 2009
The DAC712 digital inputs are TTL-compatible (1.4V Figure 10 illustrates the relationship of offset and gain
switching level) with low-leakage, high-impedance adjustments for a bipolar connected D/A converter.
inputs. Thus, the inputs are suitable for being driven Offset should be adjusted first to avoid interaction of
by any type of 5V logic such as 5V CMOS logic. An adjustments. Table 1 shows calibration values and
equivalent circuit of a digital input is shown in codes. These adjustments have a minimum range of
Figure 9 . ± 0.3%.
Data inputs float to logic '0' and control inputs float to
logic '0' if left unconnected. It is recommended that
any unused inputs be connected to DCOM to improve
noise immunity.
Digital inputs remain high-impedance when power is
off.
Figure 10. Relationship of Offset and Gain
Figure 9. Equivalent Circuit of Digital Inputs
Adjustments
Table 1. Digital Input and Analog Output Voltage
Calibration Values
The DAC712 is designed to accept positive-true
binary twos complement (BTC) input codes that are
DAC712 CALIBRATION VALUES
1 LEAST SIGNIFICANT BIT = 305 µ V
compatible with bipolar analog output operation. For
bipolar analog output configuration, a digital input of
DIGITAL INPUT
CODE BINARY
7FFFh gives a positive full-scale output, 8000h gives
TWOS
a negative full-scale output, and 0000h gives bipolar
COMPLEMENT, ANALOG OUTPUT
zero output.
BTC (V) DESCRIPTION
Positive Full-Scale –
7FFFh +9.999695
1LSB
4000h +5.000000 3/4 Scale
The DAC712 contains a +10V reference.
0001h +0.000305 BPZ + 1LSB
The reference output may be used to drive external
0000h 0.000000 Bipolar Zero (BPZ)
loads, sourcing up to 2mA. The load current should
FFFFh – 0.000305 BPZ – 1LSB
be constant, otherwise the gain and bipolar offset of
the converter will vary.
C000h – 5.000000 1/4 Scale
8000h – 10.00000 Negative Full-Scale
The output amplifier of the DAC712 is committed to a
± 10V output range. The DAC712 provides a ± 10V
Apply the digital input code that produces the
output swing while operating on ± 11.4V or higher
maximum negative output voltage and adjust the
voltage supplies.
offset potentiometer or the offset adjust D/A converter
for – 10V.
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